Combined lead wire insulator and current overload protecting device for electrical apparatus



SW@ gp 3935 w. s. MERKLE COMBINED LEAD WRE INSULATOR AND CURRENT OVERLOAD PROTECTING DE Origln VICE FOR ELECTRICAL APPARATUS al Filed July 30, 1934 Patented Sept. 8, 1935 UNETED STTES PATENT OFFICE William S. Merkle, St. Louis, Mo., assigner t Moloney Electric Company, St. Louis, Mo., a

corporation of Delaware Original application July 30, 1934, Serial No.

737,606. Divided and this application Decem ber 5, 1934, Serial No. 756,071

l. Claim.

This invention relates to a combined lead wire insulator and overload protecting device for transformers and other electrical apparatus, my present application being a division of my pending app-lication for patent Serial No. 737,606, for Combined lead wire insulator and protecting device for electrical apparatus, filed July 30, 1934.

The main object of my invention is to overcome the necessity of employing two separate and distinct, separately mounted devices, to insulate the lead wires of a transformer or other electrical apparatus, and to protect parts of the apparatus against injury from overload currents.

To this end I have devised a new accessory for transformers and other electrical apparatus, constructed in the form of a single unit that performs the dual function of an insulator bushing for a lead wire or other conductor that passes through a metal tank or casing, and a current overload protecting device consisting of a safety fuse, circuit breaker or similar device.

Figure 1 of the drawing is a vertical sectional View of a combined lead wire insulator and fuse for transformers, constructed so as to be supported laterally in the side wall of the transformer casing or tank; and

Figure 2 is a side elevational View of an adapter bar or rod of relatively heavy current carrying capacity, that may be substituted for the fuse wire of the device illustrated in Figure 1, thereby converting the device of Figure l into a combined lead wire insulator and disconnecting switch.

In Figure 1 of the drawing I have illustrated my invention embodied in a combined transformer lead wire insulator bushing and current overload protecting device, constructed so as to provide for free passage for normal currents between the transformer and connecting lines through the transformer leads, and also to protect the transformer coils and insulation against injury, resulting from overload currents. Said device comprises a body portion consisting of a single member I of porcelain or other di-electric material, designed so as to be mounted on the transformer casing in such a way that a portion of said member l is arranged on the interior of the transformer casing and a portion of said member is arranged on the exterior of said casing. In the external portion of the member I, namely, the part that is arranged on the outside of the transformer casing. there is a chamber which contains two spaced contacts or terminals, and a removable bridging means that normally establishes electrical connection between said terminals, one of said terminals being electrically connected with a coil of the transformer and the other terminal being electrically connected with a supply line. Preferably, the transformer coil terminal is combined wtih an electrical conductor that is imbedded in a web part of the member I which forms, in effect, a dividing wall between the internal portion of said member that projects into the interior of the transformer casing, and the chamber in the external portion of said member in which the terminal bridging means is arranged. In the preferred form of my invention herein illustrated the internal portion of the member I is designed so as to fit into an orice through the metal of the transformer casing and be held in position by any suitable means, such, for example, as a retaining collar 2. Mounted in the member I adjacent the internal portion of said member is a conductor 3 that is snugly imbedded in a web part of sai-d member, which forms, in effect, a dividing wall between the internal portion of said member and the chamber previously referred to, in the external portion of the member I. The conductor 3 is formed preferably by a stud provided at its inner end with a suitable means for attaching it to a lead wire 4 of a coil of the transformer, and provided at its opposite end or outer end with a Contact 5 that is arranged within the chamber just referred to. Also arranged inside of said chamber is a conventional removable fuse consisting of a fiber body or tube 6 provided at one end with a contact I that engages the contact 5 of the conductor 3. At the opposite end of said tube 6 is a contact 8 that engages a line terminal 9 rigidly fastened to the body portion I of the device and adapted to be attached to an outside line or circuit I 0. Positioned on the interior of the tube 6 is a fuse element II that constitutes an electrical bridging means across the two terminals 5 and 9, and at the outer end of said tube is a finger piece or hand grip l2 made of insulating material, so as to facilitate safe handling of the fuse.

If desired, an adap-ter rod of electrical conducting material, may be substituted for the fuse element Il, previously described, that is positioned in the body portion I of the device, said adapter rod being designated by the reference character I3 in Figure 2. When the device is equipped with such an adapter rod it serves as a combination transformer lead wire bushing and disconnecting switch. Obviously, any other suitable type or kind of safety fuse or circuit breaking device may be substituted for the one shown in Figure 1.

The device above described embodies the dual characteristics of the two separate and distinct, separately mounted devices heretofore employed to insulate a transformer lead wire and to pro'- tect the transformer or the parts of same from injury or destruction, caused by overload currents, and it has the advantages of being inexpensive to construct and easy to install. Instead of mounting the device on the side wall of the transformer tank, it may be mounted on the top o1' cover, or in any position on the casing.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

A combined transformer lead wire insulator and current cut-out devicey comprising a member of di-electric material provided with an internal portion adapted to be positioned on the inside of the transformer casing, and an external portion adapted to be positioned on the outside of the transformer casing, a chamber in said external portion separated from the internal portion of said member by an integral web part of said member, a lead Wire stud imbedded in said web p-art and provided with a transformer coil terminal arranged in said chamber, a line terminal in said chamber arranged in spaced relationship with said transformer coil terminal, and a removable means positioned in said chamber for electrically bridging across said two terminals.

Y VWILLIAM S. MERKLE. 

